Ligand Field Theory and MO Diagrams

Construct a molecular orbital diagram for an octahedral transition metal complex [ML6] considering only σ-bonding. (a) Identify which metal orbitals participate in bonding and which are non-bonding. (b) For a d6 low-spin complex like [Co(NH3)6]3+, fill in the MO diagram and calculate the CFSE. (c) How does π-backbonding with CO ligands modify this diagram and affect Δo? (d) Why is [CoF6]3- high-spin while [Co(NH3)6]3+ is low-spin?